JPS58114979A - Print hammer for printer - Google Patents

Abstract

PURPOSE:To improve the wear resistance of the printing surface and a driving section with a lighter print hammer by hardening a coat of metal or alloy applied on the printing surface and the driving section of the print hammer made of Ti based alloy. CONSTITUTION:A coat of metal of Al, Ni, Cr, and Co or an alloy thereof is applied on the printing surface 3 and a driving section 4 requiring wear resistance of a print hammer 1 for a printer employing Ti based alloy having (alpha+beta) type system in which the ratio of beta phase is below 20% as material and hardened by a treatment in a nitriding or carburizing atmosphere. This produces a print hammer with a higher reliability and an excellent wear resistance to ensure the print frequency of more than 10<8> times.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printing machine with an improved surface hardening treatment method in order to enable high-speed printing with an impact printer.

FIG. 1 shows the printing mechanism of an impact printer using a printing hammer. When the magnet coil is energized, the armature 9 is attracted by the attractive force of the magnet core, and at this time, the tip of the actuator 7, which is integrated with the armature 9, or its striking surface 8, strikes the drive section 4 of the printing hammer 1. to hit. At this time, the printing hammer 1 moves the printing surface 3 in the direction of the type conveyor 14 using the rotating shaft 5 as a fulcrum, so that the printing surface 3 collides with the printing type 14 via the printing paper and the ink ribbon 16. , to form predetermined characters on the printing paper 15.

Since the advanced printing mechanism is capable of high-speed printing, the functions required of the printing hammer 1 are weight reduction, abrasion resistance of the printing surface 3 and drive unit 4, toughness to prevent breakage, and 1. processing accuracy. This includes workability, etc. to improve the quality.

As a measure to reduce weight, its shape is as shown in Figure 2.
In order to obtain a predetermined printing quality, a shape in which the printing surface 3 is enlarged and the intermediate body portion 2 is thinned is suitable.

Conventionally, a printing hammer l for an impact printer has been used by subjecting a steel material to surface hardening treatment such as carburizing and quenching. However, with steel materials, there is a limit to how high the printing speed can be increased due to the relationship between strength and mass.

However, there is a growing demand for faster impact printers. Here, there is a correlation between the printing speed and the mass of the printing hammer l, and although it varies depending on the printing mechanism etc., an example is K as shown in FIG.

In order to increase the printing speed, it is essential to reduce the weight of the printing hammer l.

As mentioned above, if a single steel material is used for a high-speed printing system in which the printing speed is 2.0006/min or more, it will be necessary to make each part thinner due to mass limitations, but this will lead to a problem in terms of strength. Therefore, titanium alloys, aluminum alloys, plastics, etc. are considered as materials that satisfy the above requirements for toughness and density. Judging from the viewpoints of toughness, workability, surface treatment, and price, titanium-based alloys are desirable. However, titanium-based alloys include titanium alloys, α-type alloys, (α+β)-type alloys, and β-type alloys, but none of them have sufficient wear resistance. Therefore, in order to use titanium-based alloys for printing on impact printers, a surface treatment method is required that improves the abrasion resistance of the printing surface 3 and drive unit 4 without impairing the inherent toughness of the titanium-based alloys. become.

As a surface treatment method, effective local surface treatment is to harden only the printing surface 3 and the drive unit 4, such as thermal spraying and plating.

However, the hardened layer obtained by thermal spraying cannot be used with a printing hammer.
It has the disadvantage of peeling off due to harsh blows. In addition, plating has the same drawbacks as thermal spray coating, such as peeling, and plating itself on titanium alloys is extremely difficult.To solve these problems, new local surface treatments have been developed to satisfy the above functions. Printing by printing was required.

An object of the present invention is to provide an impact printer that eliminates the drawbacks of the prior art described above, reduces the weight of the printing head, and improves the abrasion resistance of the printing surface and drive part without impairing the toughness of the body. The goal is to obtain a printable number for printing.

The present invention uses a titanium-based alloy as a material for ink printers that require high speed printing, and uses a titanium-based alloy as a material to make the printing printer at a high speed. It features a printing hammer that has been subjected to surface hardening treatment and has high reliability and excellent wear resistance.

This is a printing machine using titanium alloy as the material, and local KR is applied only to the printing surface and drive part that require wear resistance.
In order to harden the print surface using the surface hardening treatment method, metals or alloys such as aluminum, nickel, chromium, cobalt, etc. are coated only on the printing surface and the necessary parts of the drive section, and then heat treated in a nitriding or carburizing atmosphere. In this case, it is preferable to heat the printing surface of the printing hammer in a nitriding atmosphere.
] In order to obtain the wear resistance of the part, a hardened layer of a certain thickness or more is required. When the thickness of the hardened layer is 3 μm or less, the hardened layer is worn out after about 1 fJ6 printings, and printing becomes impossible due to subsequent wear. Therefore, the thickness of the cured layer is 5 μm or more,
Desirably, the thickness is about 10 μm or more.

In order to obtain this hardened layer, it is necessary to coat the printing surface and the drive part with a metal or alloy such as aluminum or nickel, and then heat it at a temperature of 800° C. or higher in a nitrogen atmosphere. However, in titanium-based alloys, heating causes structural changes, and the β phase precipitates from the α phase, resulting in a decrease in the strength of the material, which poses a problem that can lead to breakage of the body. To prevent this, it is necessary to keep the heating temperature low and to shorten the processing time. Preferably, only the printing surface and the drive section are heated, or the body section is coated with an anti-nitriding film.

Here, the relationship between the amount of β phase present in the body and the number of printings leading to breakage is shown in FIG. 4. Printing: In order to obtain the number of printings above the d order normally required for printing, the amount of β phase must be suppressed to 20% or less.

On the other hand, during the hardening process, it is desirable that there is no KFi hardened layer in the body part, but it may be hardened in some cases. If a hardened layer is present in a part where toughness is required, especially in a thin wall part such as the body part, this may become a notch and break during operation.

FIG. 5 shows experimental results regarding the thickness of the cured layer in the body and the number of printings until breakage occurs. #1 printing with less hardened layer
・For K, which has a long service life and can be printed more than 1♂ times, it is necessary to suppress the thickness of the cured layer to 0.15- or less of the plate thickness.

The present invention uses a titanium-based alloy as the material for a printing hammer for printers, coats the printing surface and drive part with a metal or alloy such as aluminum or nickel only on the parts that increase the wear resistance, and then puts it in a nitrogen atmosphere. Due to the heating process,
Relating to a printing hammer for printers, which takes advantage of the fact that a hardened layer can be obtained dramatically in coated areas compared to other areas, thereby achieving and suppressing abrasion resistance of printing surfaces and drive parts. I'm full of things.

An example of a printing hammer for an impact printer using (α+β) type titanium alloy as a material will be explained.

FIG. 2 shows the shape of the printing hammer l. The parts that require a hardened layer to prevent printing defects due to abrasion are the printing surface 3 and the drive part 4, and the body part 2 is a part where it is desirable that there is no reverse pressure hardened layer.

FIG. 6 shows the relationship between the number of prints and the amount of wear on the worn surface. In this case, if the amount of wear of the printing hammer l exceeds 5 μm, it will cause problems with printing, so the predetermined number of printing times is 10.
In order to achieve 8 or more times, it is necessary to ensure that the curing depth of the printing surface 3 and the drive unit 4 is at least 5 μm or more, preferably 1 μm or more.

On the other hand, however, from the relationship between the number of times of printing until breakage in the body portion 2 shown in FIG. 5 and the depth of the hardened layer, the number of times of printing is significantly reduced if the hardened layer, which is the thinnest part, exists. Therefore, from Fig. 5, in order to achieve the desired number of printing times of 8 times, the hardening depth of the body part 2 must be set to 0.1 with respect to the plate thickness.
It is necessary to suppress it to 5% or less.

Next, the structure of the titanium alloy will be explained. (α+β)
Type titanium alloy has a phase transformation of β/(α+β) in the temperature range of 9LJθ to 10oO°C, and when heated to a temperature around this temperature, there is a structural change, that is, a quantitative difference between the α phase and the β phase. , the relationship will change and the toughness will be significantly affected.

From the relationship between the amount of β phase and the number of printings leading to breakage shown in Figure 4, in order to obtain a number of printings of 108 times or more, it is necessary to suppress the amount of β phase in the body part 2, which is the thinnest part, to 20 inches or less. There is.

Based on the above experimental results, in the present invention, in order to obtain the target printing number for printers, the printing surface 3 and drive unit 4, which require wear resistance, are coated with aluminum, and further,
Nickel was coated thereon and heated in a nitrogen atmosphere.

As a result of heat treatment for 8 (capital) 0C x 5 hours using this method, it was confirmed by hardness measurement using a Vickers hardness meter and microstructure observation using a microscope that the hardened layer of the printing surface 3 and the drive section 4 was As shown in the figure, the target thickness of 10 μm or more was obtained. On the other hand, the hardened layer of the body part 2 has a thickness of 0.1
It was possible to suppress the ratio of β phase to 5% or less and to 20% or less.

According to the present invention, in a printing hammer for a high-speed impact printer, the material is made of a titanium alloy to reduce the weight.
The desired hardened layer is applied only to the printing surface and the driving part that require wear resistance, and the hardened layer in the body part is kept below the plate thickness u, tsl, and the amount of β phase in the body part is 20-20 or less. As a result, the original strength of the titanium-based alloy was not compromised, and as a result, it was possible to print more than 108 times.

[Brief explanation of the drawing]

Figure 1 is a side view showing an outline of the printing mechanism of an impact printer, Figure 2 is a plan view and side view showing an example of a printing hammer, and Figure 3 is a characteristic diagram showing the relationship between the mass of the printing hammer and printing speed. , Fig. 4 is a characteristic diagram showing the relationship between the proportion of β phase in the body of the printing hammer and the number of printings until the body breaks, and Fig. 5 shows the hardened layer of the body and the number of printings until the body breaks. FIG. 6 is a characteristic diagram showing the relationship between the amount of wear of the printing hammer and the number of times of printing, and FIG. 7 is a curve diagram showing the cross-sectional hardness distribution of the printing hammer. In the figure, 1 is a printing hammer, 2 is a body, 3 is a printing surface, 4 drive parts, 5 is a rotating shaft, 6.11 is a return spring, 7 is an actuator, 8 is a striking surface, 9 is an armature, 12Fi magnetic core, B is magnetic coil,
14 is a type carrier, 15 is printing paper, and numeral is an ink ribbon. Patent Applicant Name Hitachi Koki Co., Ltd. Olll121 Age 2 Figures Hf Science I & (Using/Intermediate) Decoy 4 Honshi υ Lecture n Ikut% Call Attendance◆((田)(%)

Claims (1)

[Scope of Claims] α) For a printer characterized in that the material is a titanium-based alloy, the printing surface and drive part that require wear resistance are coated with metal or alloy, and then hardened by hardening treatment. Printing/
・Nma. c2)! In claim 1, the titanium alloy structure of the body is an (α+β) phase, and the proportion of the β phase is 2ot.
s or less, and the depth of the hardened layer in the body part is less than or equal to the plate thickness cL1596. G3) The printing hammer for a printer according to claim 1, wherein the material of the coating is a metal or alloy of aluminum, nickel, chromium, or cobalt. (4) A printing hammer for a printer according to claim 1, characterized in that the hardening treatment is by nitriding treatment.